The QO-100/Es’hail program can be used to transmit and receive signals to/from the Qatari Oscar 100 /Es’hail 2 geostationary satellite.
Generic block schematic showing how to use an RFzero for a QO-100 LNB-transverter-radio solution. The multipliers and band pass filters may not be needed in the specific implementation.
The configuration is done through the USB port.
The RFzero pin A0 detects if the radio in TX- or RX-mode. When in TX-mode the TX LED is lit. This TX-RX-mode is only enabled if the two frequencies (f1tx and f1rx) are different.
When GPS signals are received the PPS LED flashes ones per second and when the status of the GPS signal is valid the Valid LED is lit.
Lars, OZ1BXM, is using his RFzero as a rock stable LNB GPSDO solution for his QO-100/Es’hail station.
The RFzero inside a box. Picture courtesy Lars, OZ1BXM.
You can see much more of Lars’s, OZ1BXM, Rock Stable 10 GHz LNB solution here.
Bent, OZ1CT, has made a very professional like outdoor unit with an RFzero, transverter and PA.
The outdoor unit. Picture courtesy Bent, OZ1CT.
Hans, OZ2XH, uses his RFzero with the QO-100 program for his QO-100 transverter connected to his IC-7300.
QO-100 transverter with display. Picture courtesy Hans, OZ2XH.
Leif’s, OZ9F, RFzero and OZ5N QO-100 transverter solution. Picture courtesy Leif, OZ9F.
The RFzero is used as a dual local oscillator for a LNB-transverter in combination with an IF-radio. The program is capable of generating one fixed frequency, e.g. for a fixed local oscillator for a LNB that typically uses 25 MHz, and a second frequency pair that can be used for transmit and receive local oscillators for mixers that are connected to the transceiver. None of the frequencies have to be related in any way and can be anywhere in the fundamental frequency range the Si5351A can generate. All the frequencies are GPS locked, if the GPS is valid, thus you will be spot on on both 2,4 GHz and 10 GHz.
To get two local oscillator signals you need to remove T1. Then either short the C40 to Z1 path, f0 will then be on the SMA connector, and mount a U.FL connector on CON5. Alternatively mount two U.FL connectors using the CON4, f0 will then be on the CON4 connector, and CON5 pads. The transmit/receive local oscillator frequencies are always found on CON5.
Whether the band pass filters and/or multipliers are needed depends on the actual implementation, e.g. many SDRs are able to receive directly on the LNB output frequency.
You may also use one of the harmonics from the RFzero as local oscillator.
To setup the type of display used please use the “wr display” command. If you want to change what is shown on the display please edit the display.cpp file.
The display shows the UTC, the GPS status, the transmit/receive status, the number of satellites and the HDOP.
Example of an LCD 16×2.
The display is a LCD (4×20) that shows the UTC, the transmit/receive status, GPS status, the number of satellites, the HDOP, call sign and locator.
Example of an LCD 20×4.
The configuration of the program is done via the USB port, 9600 Baud, 8 bits, no parity and one stop bit, using a terminal program (e.g. Arduino IDE Serial Monitor, Termite Terminal (Windows), CuteCom (Linux) or Terminal (Mac OS)). Please connect the RFzero via a USB B cable to your computer and connect the terminal program to the right COM port in the terminal program. The RFzero identifies itself as an Arduino Zero (Windows Device Manager).
If you don’t see the RFzero> or RFzero config> prompts please press the enter key. When you want to execute a command you don’t have to enter the prompt but only the command and parameters after the >.
Changes to the configuration does not take effect before leaving the configuration mode.
All input to the RFzero must be in lowercase.
To enter the configuration mode please enter config at the RFzero> prompt, i.e.
To see the available commands please enter ? at the RFzero config> prompt, i.e.
RFzero config> ?
To leave the configuration mode please enter exit at the RFzero config> prompt, i.e.
RFzero config> exit
When in configuration mode, i.e. when you see the RFzero config> prompt, the most frequent commands are
to see the configuration that will be used after exiting the configuration mode.
wr t1 MODE
to set the T1 H/W mode where MODE is
- 0: Transformer (default)
- 1: Combiner
- 2: None
wr display MODE
to set the display mode where MODE is
- 0: None
- 1: LCD 16 characters and two lines, HD44780 interface
- 2: LCD 20 characters and four lines, HD44780 interface
- 3: LCD 16 characters and two lines, HD44780 via I2C PCF8574 interface
- 4: LCD 20 characters and four lines, HD44780 via I2C PCF8574 interface
- 5: Graphics display, ILI9341 SPI interface
- 6: Graphics display, ILI9488 SPI interface
wr call CALL
where CALL is your call sign shown on the display if any. Max length is ten characters.
wr loc LOCATOR
where LOCATOR is your locator shown on the display if any.
wr f0 FREQ MULTI
where FREQ is the fixed frequency in Hz, e.g. that is used for the LNB, and MULTI is the multiplication factor used. Set the multiplication to one (1) if no multiplier is used.
wr f1rx FREQ MULTI
where FREQ is the receive local oscillator frequency in Hz and MULTI is the multiplication factor used. Set the multiplication to one (1) if no multiplier is used. If f1rx is identical to f1tx, incl. multipliers, there is no TX-RX functionality.
wr f1tx FREQ MULTI
where FREQ is the transmit local oscillator frequency in Hz and MULTI is the multiplication factor used. Set the multiplication to one (1) if no multiplier is used. If f1tx is identical to f1rx, incl. multipliers, there is no TX-RX functionality.
wr level LEVEL
where LEVEL is the drive strength current in the output stages. This effectively changes the output power by up to 10 dB, but varies somewhat with frequency. Valid LEVEL values are
- 0: 2 mA
- 1: 4 mA
- 2: 6 mA
- 3: 8 mA, default level
To read more about the drive strength current please consult the Si5351A datasheet.
More commands are available so please enter a question mark (?) at the RFzero config> prompt to see them.
Bent, OZ1CT, has made two videos one showing his out door unit, and the other shows his radio listening to the beacon and a QSO. As you can see there is no cover over the crystal. The fan inside the outdoor unit creates some perturbations even if it is a closed cabinet.
Here is a video by Anders, OZ3Z of a, low pitched, QSO.
Here is a recording made by Leif, OZ9F, of his own signal.
Ole, OZ2OE, made a comparison of the stability of the RFzero vs. two OCXO controlled LOs for his QO-100 setup locked at 10 MHz. The OXCOs are slightly better than the RFzero. However, the RFzero does the job in the real world without any noticeable distortion.
5 MHz from an NDK OCXO and multiplied by two to reach 10 MHz. Picture courtesy Ole, OZ2OE.
10 MHz from a Telequartz OCXO. Picture courtesy Ole, OZ2OE.
10 MHz from an RFzero. Picture courtesy Ole, OZ2OE.
Steen, OZ5N, has also made a plot of the QO-100 beacon when keying.
The 1300 Hz trace is only present when the beacon is sending CW FSK at 1100 Hz and 1500 Hz. Picture courtesy Steen, OZ5N.